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CHEMICAL ENGINEERING (192 journals)                     

Showing 1 - 192 of 192 Journals sorted alphabetically
AATCC Journal of Research     Full-text available via subscription   (Followers: 7)
ACS Sustainable Chemistry & Engineering     Hybrid Journal   (Followers: 5)
Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials     Hybrid Journal   (Followers: 5)
Acta Polymerica     Hybrid Journal   (Followers: 9)
Additives for Polymers     Full-text available via subscription   (Followers: 21)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 7)
Advanced Chemical Engineering Research     Open Access   (Followers: 32)
Advanced Powder Technology     Hybrid Journal   (Followers: 17)
Advances in Applied Ceramics     Hybrid Journal   (Followers: 5)
Advances in Chemical Engineering     Full-text available via subscription   (Followers: 25)
Advances in Chemical Engineering and Science     Open Access   (Followers: 55)
Advances in Polymer Technology     Hybrid Journal   (Followers: 13)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 7)
Annual Review of Analytical Chemistry     Full-text available via subscription   (Followers: 10)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 12)
Anti-Corrosion Methods and Materials     Hybrid Journal   (Followers: 10)
Applied Petrochemical Research     Open Access   (Followers: 2)
Asia-Pacific Journal of Chemical Engineering     Hybrid Journal   (Followers: 8)
Biochemical Engineering Journal     Hybrid Journal   (Followers: 14)
Biofuel Research Journal     Open Access   (Followers: 4)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 10)
Brazilian Journal of Chemical Engineering     Open Access   (Followers: 3)
Bulletin of Chemical Reaction Engineering & Catalysis     Open Access   (Followers: 2)
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 2)
Carbohydrate Polymers     Hybrid Journal   (Followers: 8)
Catalysts     Open Access   (Followers: 8)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 1)
Chemical and Engineering News     Free   (Followers: 13)
Chemical and Materials Engineering     Open Access   (Followers: 13)
Chemical and Petroleum Engineering     Hybrid Journal   (Followers: 13)
Chemical and Process Engineering     Open Access   (Followers: 27)
Chemical and Process Engineering Research     Open Access   (Followers: 24)
Chemical Engineering & Technology     Hybrid Journal   (Followers: 32)
Chemical Engineering and Processing: Process Intensification     Hybrid Journal   (Followers: 17)
Chemical Engineering and Science     Open Access   (Followers: 19)
Chemical Engineering Communications     Hybrid Journal   (Followers: 14)
Chemical Engineering Education     Full-text available via subscription  
Chemical Engineering Journal     Hybrid Journal   (Followers: 45)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 23)
Chemical Engineering Research Bulletin     Open Access   (Followers: 12)
Chemical Engineering Science     Hybrid Journal   (Followers: 27)
Chemical Geology     Hybrid Journal   (Followers: 19)
Chemical Papers     Hybrid Journal   (Followers: 2)
Chemical Product and Process Modeling     Hybrid Journal   (Followers: 4)
Chemical Reviews     Full-text available via subscription   (Followers: 176)
Chemical Society Reviews     Full-text available via subscription   (Followers: 41)
Chemical Technology     Open Access   (Followers: 16)
ChemInform     Hybrid Journal   (Followers: 8)
Chemistry & Industry     Hybrid Journal   (Followers: 5)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry of Materials     Full-text available via subscription   (Followers: 257)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 15)
ChemSusChem     Hybrid Journal   (Followers: 7)
Chinese Chemical Letters     Full-text available via subscription   (Followers: 2)
Chinese Journal of Chemical Engineering     Full-text available via subscription   (Followers: 4)
Chinese Journal of Chemical Physics     Hybrid Journal   (Followers: 1)
Coke and Chemistry     Hybrid Journal   (Followers: 1)
Coloration Technology     Hybrid Journal   (Followers: 1)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 12)
Computer Aided Chemical Engineering     Full-text available via subscription   (Followers: 1)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 9)
CORROSION     Full-text available via subscription   (Followers: 20)
Corrosion Engineering, Science and Technology     Hybrid Journal   (Followers: 36)
Corrosion Reviews     Hybrid Journal   (Followers: 6)
Crystal Research and Technology     Hybrid Journal   (Followers: 6)
Current Opinion in Chemical Engineering     Open Access   (Followers: 7)
Designed Monomers and Polymers     Open Access   (Followers: 2)
Education for Chemical Engineers     Hybrid Journal   (Followers: 5)
Eksergi     Open Access  
Emerging Trends in Chemical Engineering     Full-text available via subscription   (Followers: 3)
European Polymer Journal     Hybrid Journal   (Followers: 41)
Fibers and Polymers     Full-text available via subscription   (Followers: 6)
Fluorescent Materials     Open Access   (Followers: 1)
Focusing on Modern Food Industry     Open Access   (Followers: 2)
Frontiers of Chemical Science and Engineering     Hybrid Journal   (Followers: 2)
Gels     Open Access  
Geochemistry International     Hybrid Journal   (Followers: 2)
Handbook of Powder Technology     Full-text available via subscription   (Followers: 6)
Heat Exchangers     Open Access   (Followers: 3)
High Performance Polymers     Hybrid Journal   (Followers: 1)
Hungarian Journal of Industry and Chemistry     Open Access  
Indian Chemical Engineer     Hybrid Journal   (Followers: 5)
Indian Journal of Chemical Technology (IJCT)     Open Access   (Followers: 10)
Indonesian Journal of Chemical Science     Open Access   (Followers: 1)
Industrial & Engineering Chemistry     Full-text available via subscription   (Followers: 11)
Industrial & Engineering Chemistry Research     Full-text available via subscription   (Followers: 21)
Industrial Chemistry Library     Full-text available via subscription   (Followers: 3)
Industrial Gases     Open Access  
Info Chimie Magazine     Full-text available via subscription   (Followers: 3)
International Journal of Chemical and Petroleum Sciences     Open Access   (Followers: 3)
International Journal of Chemical Engineering     Open Access   (Followers: 7)
International Journal of Chemical Reactor Engineering     Hybrid Journal   (Followers: 3)
International Journal of Chemical Technology     Open Access   (Followers: 5)
International Journal of Chemoinformatics and Chemical Engineering     Full-text available via subscription   (Followers: 2)
International Journal of Food Science     Open Access   (Followers: 3)
International Journal of Industrial Chemistry     Open Access   (Followers: 1)
International Journal of Polymeric Materials     Hybrid Journal   (Followers: 6)
International Journal of Waste Resources     Open Access   (Followers: 4)
Journal of Chemical Engineering & Process Technology     Open Access   (Followers: 5)
Journal of Applied Crystallography     Hybrid Journal   (Followers: 6)
Journal of Applied Electrochemistry     Hybrid Journal   (Followers: 14)
Journal of Applied Polymer Science     Hybrid Journal   (Followers: 135)
Journal of Biomaterials Science, Polymer Edition     Hybrid Journal   (Followers: 9)
Journal of Bioprocess Engineering and Biorefinery     Full-text available via subscription  
Journal of Chemical & Engineering Data     Full-text available via subscription   (Followers: 11)
Journal of Chemical and Biological Interfaces     Full-text available via subscription   (Followers: 1)
Journal of Chemical Ecology     Hybrid Journal   (Followers: 6)
Journal of Chemical Engineering     Open Access   (Followers: 20)
Journal of Chemical Engineering and Materials Science     Open Access   (Followers: 2)
Journal of Chemical Science and Technology     Open Access   (Followers: 4)
Journal of Chemical Sciences     Partially Free   (Followers: 19)
Journal of Chemical Technology & Biotechnology     Hybrid Journal   (Followers: 10)
Journal of Chemical Theory and Computation     Full-text available via subscription   (Followers: 15)
Journal of CO2 Utilization     Hybrid Journal   (Followers: 2)
Journal of Combinatorial Chemistry     Full-text available via subscription  
Journal of Crystallization Process and Technology     Open Access   (Followers: 8)
Journal of Environmental Chemical Engineering     Hybrid Journal   (Followers: 6)
Journal of Food Measurement and Characterization     Hybrid Journal  
Journal of Food Processing & Technology     Open Access   (Followers: 1)
Journal of Fuel Chemistry and Technology     Full-text available via subscription   (Followers: 4)
Journal of Geochemical Exploration     Hybrid Journal   (Followers: 1)
Journal of Industrial and Engineering Chemistry     Hybrid Journal   (Followers: 1)
Journal of Information Display     Hybrid Journal   (Followers: 1)
Journal of Inorganic and Organometallic Polymers and Materials     Partially Free   (Followers: 9)
Journal of Modern Chemistry & Chemical Technology     Full-text available via subscription   (Followers: 2)
Journal of Molecular Catalysis A: Chemical     Hybrid Journal   (Followers: 6)
Journal of Non-Crystalline Solids     Hybrid Journal   (Followers: 8)
Journal of Organic Semiconductors     Open Access   (Followers: 5)
Journal of Physics and Chemistry of Solids     Hybrid Journal   (Followers: 5)
Journal of Polymer and Biopolymer Physics Chemistry     Open Access   (Followers: 6)
Journal of Polymer Engineering     Hybrid Journal   (Followers: 9)
Journal of Polymer Research     Hybrid Journal   (Followers: 6)
Journal of Polymer Science Part C : Polymer Letters     Hybrid Journal   (Followers: 6)
Journal of Polymers     Open Access   (Followers: 6)
Journal of Polymers and the Environment     Hybrid Journal   (Followers: 1)
Journal of Pure and Applied Chemistry Research     Open Access   (Followers: 2)
Journal of the American Chemical Society     Full-text available via subscription   (Followers: 303)
Journal of the Bangladesh Chemical Society     Open Access  
Journal of the Brazilian Chemical Society     Open Access   (Followers: 2)
Journal of The Institution of Engineers (India) : Series E     Hybrid Journal   (Followers: 1)
Journal of the Pakistan Institute of Chemical Engineers     Open Access   (Followers: 1)
Journal of the Taiwan Institute of Chemical Engineers     Hybrid Journal   (Followers: 2)
Journal of Water Chemistry and Technology     Hybrid Journal   (Followers: 9)
Jurnal Bahan Alam Terbarukan     Open Access  
Jurnal Inovasi Pendidikan Kimia     Open Access   (Followers: 5)
Jurnal Reaktor     Open Access  
Jurnal Rekayasa Kimia & Lingkungan     Open Access  
Jurnal Teknologi Dan Industri Pangan     Open Access   (Followers: 1)
Konversi     Open Access  
Korean Journal of Chemical Engineering     Hybrid Journal   (Followers: 3)
Main Group Metal Chemistry     Hybrid Journal   (Followers: 1)
Materials Chemistry and Physics     Full-text available via subscription   (Followers: 16)
Materials Science and Applied Chemistry     Open Access  
Materials Sciences and Applied Chemistry     Full-text available via subscription  
Modern Chemistry & Applications     Open Access  
Molecular Imprinting     Open Access  
Nanochemistry Research     Open Access  
Nanocontainers     Open Access   (Followers: 1)
Nanofabrication     Open Access  
Noise Control Engineering Journal     Full-text available via subscription   (Followers: 4)
Ochrona Srodowiska i Zasobów Naturalnych : Environmental Protection and Natural Resources     Open Access  
Petroleum Chemistry     Hybrid Journal   (Followers: 1)
Physics and Chemistry of Glasses - European Journal of Glass Science and Technology Part B     Full-text available via subscription   (Followers: 4)
Plasma Processes and Polymers     Hybrid Journal   (Followers: 3)
Plasmas and Polymers     Hybrid Journal  
Polymer     Hybrid Journal   (Followers: 180)
Polymer Bulletin     Hybrid Journal   (Followers: 7)
Polymer Composites     Hybrid Journal   (Followers: 15)
Polyolefins Journal     Open Access  
Powder Technology     Hybrid Journal   (Followers: 13)
Recyclable Catalysis     Open Access   (Followers: 1)
Research on Chemical Intermediates     Hybrid Journal  
Reviews in Chemical Engineering     Hybrid Journal   (Followers: 5)
Revista ION     Open Access  
Revista Mexicana de Ingeniería Química     Open Access  
Rubber Chemistry and Technology     Full-text available via subscription   (Followers: 2)
Russian Chemical Bulletin     Hybrid Journal   (Followers: 2)
Russian Journal of Applied Chemistry     Hybrid Journal   (Followers: 1)
Science and Engineering of Composite Materials     Hybrid Journal   (Followers: 61)
Solid Fuel Chemistry     Hybrid Journal  
South African Journal of Chemical Engineering     Open Access   (Followers: 2)
South African Journal of Chemistry     Open Access   (Followers: 2)
Surface Engineering and Applied Electrochemistry     Hybrid Journal   (Followers: 6)
Sustainable Chemical Processes     Open Access   (Followers: 2)
Synthesis Lectures on Chemical Engineering and Biochemical Engineering     Full-text available via subscription  
The Canadian Journal of Chemical Engineering     Hybrid Journal   (Followers: 3)
The Chemical Record     Hybrid Journal   (Followers: 1)
Theoretical Foundations of Chemical Engineering     Hybrid Journal   (Followers: 2)
Transition Metal Chemistry     Hybrid Journal   (Followers: 4)
Transylvanian Review of Systematical and Ecological Research     Open Access  
Visegrad Journal on Bioeconomy and Sustainable Development     Open Access   (Followers: 2)
Zeitschrift für Naturforschung B : A Journal of Chemical Sciences     Open Access   (Followers: 1)


Journal Cover Chemical Engineering Science
  [SJR: 1.073]   [H-I: 135]   [27 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0009-2509
   Published by Elsevier Homepage  [3044 journals]
  • Fungi residue derived carbon as highly efficient hydrogen peroxide
    • Abstract: Publication date: 31 December 2017
      Source:Chemical Engineering Science, Volume 174
      Author(s): Zhu Meng, Juntao Li, Feng Huo, Yan Huang, Zhonghua Xiang
      In electrochemical devices, the reduction of dissolved oxygen in electrolyte can achieve on-site production of hydrogen peroxide. The industrial viability of the process strongly depends on cathode electrocatalyst. However, current catalysts rely on rare, noble metals and their composite. Thus, it remains a great challenge of cost-effective catalyst with both high activity and selectivity. Herein, we made use of extremely low-cost fungi residue biomass, developing a multi-non-precious metal doped carbon catalyst (named as FRC) for H2O2 electrogeneration by facile in-situ synthesis. The one-step prepared FRC balances the performance of different metal oxides and exhibits not only high activity but also high selectivity at a spacious potential range. Specifically, the current density for ring reaches 0.45mAcm−2 at −0.5V (vs SCE). Besides, the selectivity achieves 98% and remain above 91% in wide potential range (−0.7∼−0.3V), which exceeds almost all metal contained carbon materials to our knowledge. As the first study of fungi residue towards H2O2 electrogeneration, this novel approach provides a highly promising and low cost electrocatalyst for real production, moreover, exploring a new direction for H2O2 electrocatalyst development.
      Graphical abstract image

      PubDate: 2017-09-20T07:38:41Z
  • Atmospheric plasma spray pyrolysis of lithiated nickel-manganese-cobalt
           oxides for cathodes in lithium ion batteries
    • Abstract: Publication date: 31 December 2017
      Source:Chemical Engineering Science, Volume 174
      Author(s): Babajide Patrick Ajayi, Arjun Kumar Thapa, Uroš Cvelbar, Jacek B. Jasinski, Mahendra K. Sunkara
      Nickel manganese cobalt (NMC) oxides have been pursued for stable and high energy density cathodes in lithium ion batteries for years. The current synthesis techniques based on co-precipitation and hydrothermal techniques require reaction time scales on the order of several hours making them difficult for scale-up. Here, we present a scalable manufacturing technique based on atmospheric plasma based spray pyrolysis for producing NMC (and Li-NMC) with reaction time scales of the order of minutes. Results show that the chemistry of resulting materials (Ni/Mn/Co ratio) can be controlled from precursor composition. Specifically, the compound LiNi0.2Mn0.6Co0.2O2, is prepared by the atmospheric plasma-assisted synthesis method. The resulting LiNi0.2Mn0.6Co0.2O2 cathode material demonstrates a durable performance with an initial discharge specific capacity of 258mAhg−1 while maintaining above 210mAhg−1 after 50 cycles.
      Graphical abstract image

      PubDate: 2017-09-20T07:38:41Z
  • Investigation of the precipitation of Na2SO4 in supercritical water
    • Abstract: Publication date: 31 December 2017
      Source:Chemical Engineering Science, Volume 174
      Author(s): T. Voisin, A. Erriguible, G. Philippot, D. Ballenghien, D. Mateos, F. Cansell, B.B. Iversen, C. Aymonier
      SuperCritical Water Oxidation process (SCWO) is a promising technology for treating toxic and/or complex chemical wastes with very good efficiency. Above its critical point (374°C, 22.1MPa), water exhibits particular properties and organic compounds can be easily dissolved and degraded with the addition of oxidizing agents. But these interesting properties imply a main drawback regarding inorganic compounds. Highly soluble at ambient temperature in water, these inorganics (such as salts) are no longer soluble in supercritical water and precipitate into solids, creating plugs in SCWO processes. Although this precipitation phenomenon is well known asa limiting factor for SCWO process, it is still not well understood. This work intends to investigate the precipitation phenomenon with a new methodology. A common salt, disodium sulfate (Na2SO4), is taken asa reference for the study. Na2SO4 solubility in sub- and supercritical water is determined on a wide temperature range using a continuous set-up. Crystallite sizes formed after precipitation are measured with in situ synchrotron wide angle X-ray scattering (WAXS). Combining these experimental results, a numerical modeling of the precipitation in supercritical conditions is performed by taking into account all the implied physical phenomena: thermodynamic, hydrodynamic and nucleation & growth.
      Graphical abstract image

      PubDate: 2017-09-20T07:38:41Z
  • Optimization of axial catalyst loading in transient-operated
           zone-structured monoliths: Reduction of cumulative emissions in automotive
           oxidation catalysts
    • Abstract: Publication date: 31 December 2017
      Source:Chemical Engineering Science, Volume 174
      Author(s): Sivaram Kannepalli, Andreas Gremminger, Steffen Tischer, Olaf Deutschmann
      A model based mathematical optimization methodology to optimize the precious metal loading profile (PGM loading) in zone-structured catalytic converters is developed. To carry out this task, a multi zone-structured optimization formulation, where the catalyst is divided into N zones axially to obtain a non uniform optimal PGM loading profile, which can be tested experimentally, is used. The effects of the PGM loading on washcoat diffusion limitations is also considered. The objective is to optimize the spatial distribution of loading for a fixed amount of precious metal to maximize the chemical conversion efficiency under transient operation. To achieve this, the transient 1D+1D model is solved with the help of implicit solver DASPKADJOINT and translated into a non-linear optimization problem that can be solved with any derivative based nonlinear programming (NLP) solvers. The model is applied to two example cases: CO oxidation on a Pt/Al2O3 based Diesel Oxidation Catalyst catalyst (minimizing cold-start emissions) and CH4 oxidation on Pd/Al2O3 (minimizing deactivation effects). In both the cases it was observed that the optimal solution with maximum PGM loading in the channel entrance region improved the performance of the catalysts. The methodology presented is generic and can be transferred to different systems with different chemistries, which may result in significantly different optimization results and loading patterns.
      Graphical abstract image

      PubDate: 2017-09-20T07:38:41Z
  • Effects of residence time on the efficiency of desulfurization and
           denitrification in the bubbling reactor
    • Abstract: Publication date: 31 December 2017
      Source:Chemical Engineering Science, Volume 174
      Author(s): Dongwei Zhang, Hanzhong Tao, Congying Yao, Zishuai Sun
      Based on bubbling reactor bottle, experimental study on the absorption of nitric oxide (NO) and sulfur dioxide (SO2) by two mixed liquid oxidants (hydrogen peroxide (H2O2) and sodium persulfate (Na2S2O8)) is performed. Setting the mixed liquid oxidants temperature of 363K, pH value of 11, mixed gas velocity of 0.3 m3/s, NO and SO2 concentration of 400ppm, when the liquid level height of the mixed liquid oxidants increasing from 20mm to 80 mm, the residence time of gas bubble in the bubbling reactor bottle increases from 0.078s to 0.259s, with the desulfurization efficiency increasing from 57.31% to 70.15% and the denitrification efficiency increasing from 14.73% to 22.29% respectively. It can be seen that the liquid level height has a decisive effect on the gas residence time, which directly affects the efficiency of desulfurization and denitrification in the bubbling reactor bottle. In order to increase the residence time of gas bubble in the liquid phase under the condition of a certain liquid level height, the spoiler elements (twist tape, helical fin and static mixer) used for heat transfer enhancement in pipe are introduced to the bubbling reactor based on numerical simulation method. The results showed that: different structural parameters of the spoiler elements have a certain role both in promoting the residence time and the efficiency of desulfurization and denitrification in the bubbling reactor.

      PubDate: 2017-09-20T07:38:41Z
  • Analysis of the propylene epoxidation mechanism on supported gold
    • Abstract: Publication date: 31 December 2017
      Source:Chemical Engineering Science, Volume 174
      Author(s): C. Heath Turner, Jingjing Ji, Zheng Lu, Yu Lei
      The direct propylene epoxidation reaction has been investigated experimentally in the past by several different groups, and gold-based catalysts tend to provide high selectivity for propylene oxide, but the conversion is relatively low. Models that can connect the atomistic catalytic details to the observed experimental data are desired, in order to identify new catalyst structures and formulations. While electronic structure calculations have been used to quantify some of the key reaction steps in the direct propylene epoxidation reaction, atomistic models for translating this information into more experimentally-relevant data are needed. Here, kinetic Monte Carlo (KMC) simulations are used to bridge this gap in the modeling hierarchy. Relevant data from previous experiments and electronic structure calculations are used to parameterize a KMC model for predicting propylene oxide production from an Au/TiO2/SiO2 catalyst. The model connects the H2/O2-related reactions occurring on the Au sites with the epoxidation step on the isolated Ti surface sites. In addition, the composition in the bulk gas phase is synchronized with the dynamic reaction events occurring on the surface. The KMC model is able to adequately reproduce the experimental trends with respect to temperature and different reactant partial pressures. However, this is only achieved by considering the re-adsorption of trace amounts of the oxidant (H2O2) from the gas phase, versus merely assuming that desorbed species are immediately swept away in the gas stream.
      Graphical abstract image

      PubDate: 2017-09-20T07:38:41Z
  • Hydrogen by chemical looping reforming of ethanol: The effect of promoters
           on La2-xMxNiO4-λ (M=Ca, Sr and Ce) oxygen carriers
    • Abstract: Publication date: 31 December 2017
      Source:Chemical Engineering Science, Volume 174
      Author(s): Qian Zhang, Lin Li, Bo Jiang, Dawei Tang, Binlin Dou
      Chemical looping reforming (CLR) of ethanol is a novel method to produce hydrogen. It’s vital to select an appropriate oxygen carrier (OC) with favorable catalytic activity and high stability for successive redox processes. In current research, the intelligent perovskites La2- xMx NiO4- λ (M =Ca, Sr and Ce) were used as OCs and prepared by co-precipitation method. The ‘intelligence’ was embodied in exceptional self-recovery ability of perovskite during oxidation stage of CLR process, which was confirmed by the movement that Ni ions escaped and regained back to original position during oxidation step. The experimental result indicated that the movement effectively restrained the growth of metallic Ni and resulted in high activity of OC during life-time service and aging. Furthermore, the influence of promoters doping on the regeneration characteristics of OCs was investigated by BET, TEM, XRD, ICP-OES, TG and a fixed-bed experiment. From the perspective of catalytic performance, the addition of promoter strongly improved the reducibility of OCs, and the optimal substitution is Ca. The LNO-Ca OC exhibited favorable reducibility of nickel ions, shorter ‘dead time’, higher yield of hydrogen, superior ethanol conversion, stronger anti-carbon ability and excellent reproducibility of perovskite during successive redox reactions.

      PubDate: 2017-09-20T07:38:41Z
  • Three-dimensional fluidized beds with rough spheres: Validation of a Two
           Fluid Model by Magnetic Particle Tracking and discrete particle
    • Abstract: Publication date: 31 December 2017
      Source:Chemical Engineering Science, Volume 174
      Author(s): Lei Yang, J.T. Padding, K.A. Buist, J.A.M. Kuipers
      Two fluid model simulations based on our recently introduced kinetic theory of granular flow (KTGF) for rough spheres and rough walls, are validated for the first time for full three-dimensional (3D) bubbling fluidized beds. The validation is performed by comparing with experimental data from Magnetic Particle Tracking and more detailed Discrete Particle Model simulations. The effect of adding a third dimension is investigated by comparing pseudo-2D and full 3D bubbling fluidized beds containing inelastic rough particles. Spatial distributions of key hydrodynamic data as well as energy balances in the fluidized bed are compared. In the pseudo-2D bed, on comparison with the KTGF derived by Jenkins and Zhang, we find that the present KTGF improves the prediction of bed hydrodynamics. In the full 3D bed, particles are more homogeneously distributed in comparison with the pseudo-2D bed due to a decrease of the frictional effect from the front and back walls. The new model results are in good agreement with experimental data and discrete particle simulations for the time-averaged bed hydrodynamics.
      Graphical abstract image

      PubDate: 2017-09-20T07:38:41Z
  • Stability analysis of bilayer polymer fiber spinning process
    • Abstract: Publication date: 31 December 2017
      Source:Chemical Engineering Science, Volume 174
      Author(s): Karan Gupta, Paresh Chokshi
      The linear stability of a bilayer fiber spinning process is analyzed for axisymmetric disturbances under isothermal conditions. The co-extruded fiber consists of two concentric layers of rheologically stratified polymeric fluids. While the core fluid is an entangled polymer melt described using the eXtended Pom-Pom (XPP) model, the sheath layer is a low molecular weight unentangled polymer modeled as an Upper Convected Maxwell (UCM) fluid. The analysis indicates that, for fast extensional flows, such an arrangement enhances the critical draw ratio of the process over that found from the spinning of XPP fluid alone, thus delaying the onset of draw resonance and stabilizing the system. Further, the range of flow Deborah number for stable spinning is found to be much broader than that for the UCM fluid alone. For low to moderately elastic flows, the stability behavior is governed mainly by the rheology of the more-elastic core layer (XPP fluid), whereas for the highly elastic flows, the stability behavior is dominated by the less-elastic sheath layer (UCM fluid). The sensitivity of the stability diagram with respect to various spinning flow parameters, like the relative fraction of core and sheath layers, the rheological stratification of two fluids, and the spine-line dimensions, has also been examined in order to identify the region of enhanced stability such that the draw resonance is suppressed.

      PubDate: 2017-09-20T07:38:41Z
  • Simulating the impacts of internals on gas–liquid hydrodynamics of
           bubble column
    • Abstract: Publication date: 31 December 2017
      Source:Chemical Engineering Science, Volume 174
      Author(s): Xiaofeng Guo, Caixia Chen
      Impacts of vertical internals on gas–liquid hydrodynamic of bubble columns were simulated using an Eulerian two fluid model coupled with a population balance method (TFM-PBM). The interfacial drag force, the shear induced lift force, and the radial wall lubrication force exerted on bubbles were included in the model. The effects of wall boundary conditions were investigated numerically. The numerical results showed the radial wall lubrication force greatly impacts the radial distribution of time-averaged gas holdup, especially in the internals affecting region. When the internals were present, the turbulent dissipation rates increased significantly in the gaps between the internal walls, and more bubbles with smaller bubble size were predicted in the bubble column. Meanwhile, the gas holdup increased with dense internals insertion, especially in r/R equal to 0.6–0.9 region. The internals and the configurations influence the overall liquid circulation. When 31 thin internals are inserted in column at a low superficial gas velocity, large scale liquid circulations are replaced by small local vortex. However, the variations of liquid circulations are different at a high superficial gas velocity, when the large scale liquid circulations are always present in the column regardless of inserting 31 thin internals or 8 thick internals.

      PubDate: 2017-09-20T07:38:41Z
  • Interface-engineered MoS2/C nanosheet heterostructure arrays for
           ultra-stable sodium-ion batteries
    • Abstract: Publication date: 31 December 2017
      Source:Chemical Engineering Science, Volume 174
      Author(s): Haiyan Wang, Hao Jiang, Yanjie Hu, Petr Saha, Qilin Cheng, Chunzhong Li
      Development of ultra-stable high capacity electrodes is imperative for the widespread commercialization of sodium-ion batteries. Herein, we employed a micro-area etching and surface functionalization strategy to synthesize two-dimensional (2D) MoS2/C nanosheets with a well-defined heterointerface vertically anchored on a carbon cloth. The large MoS2/C nanosheet heterointerface and a high interlayer distance (0.99nm) not only facilitated Na+ intercalation but also improved the diffusion kinetics of Na+ in the 2D interlayer space. A modulation of the cut-off voltage yielded a high specific capacity of 433mAhg−1 at 0.2Ag−1 and 232mAhg−1 at 10Ag−1 within the potential range of 0.4–3.0V. These values are much higher than that of pure MoS2 nanosheet arrays (162mAhg−1 at 10Ag−1). More importantly, during the first 1500 cycles, the capacity was maintained at ∼320mAhg−1 at 1Ag−1, while after 10000 cycles, it became approximately ∼271mAhg−1 at 3Ag−1. These are the best values ever reported for MoS2-based anode materials for SIBs. Furthermore, after being assembled into a flexible battery, it withstand repeated bending for over 200 times without any obvious capacity loss. Hence, this material is a promising electrode for future flexible batteries.
      Graphical abstract image

      PubDate: 2017-09-14T07:35:59Z
  • Molecular dynamics study of high temperature wetting kinetics for Al/NiAl
           and Al/Ni3Al systems: Effects of grain boundaries
    • Abstract: Publication date: 31 December 2017
      Source:Chemical Engineering Science, Volume 174
      Author(s): Lin Lin, Sheng Hui, Gui Lu, Shuo-Lin Wang, Xiao-Dong Wang, Duu-Jong Lee
      The high-temperature wetting of metal droplets on alloy metal substrates is of practical interest owing to its wide range of applications in brazing, welding and soldering. The surface and bulk of the alloy metals contain very many grain boundaries, whose effects on high-temperature wetting and the associated mechanisms have not been satisfactorily studied. In this work, two spreading scenarios are considered using molecular dynamics simulations to investigate the effects of grain boundaries on the wetting kinetics of the spreading of Al droplets on substrates with (polycrystalline NiAl) or without (monocrystalline NiAl) dissolutive reactions and at various rates of solution (monocrystalline and polycrystalline Ni3Al). Dissolutive reactions occur only when an Al droplet spreads over a polycrystalline NiAl substrate, and they significantly accelerate the wetting kinetics. Irregular atomic alignment and associated with grain boundaries, atomic migration or dissolution reactions occur more easily on grain boundaries than on ideal crystal substrates. Dissolutive reactions occur when Al droplets spread on either monocrystalline or polycrystalline Ni3Al substrates; however, grain boundaries influence the dissolution rates in various spreading stages. The dissolution rate of the Al(l)/polycrystalline Ni3Al(s) system with grain boundaries exceeds that of the Al(l)/monocrystalline Ni3Al(s) system in the initial stage of spreading, but is less than that of the Al(l)/monocrystalline Ni3Al(s) system in the final stage of spreading. Correspondingly, the spreading of the Al(l)/polycrystalline NiAl(s) system is faster than that of Al(l)/monocrystalline NiAl(s) system in the first stage but slower in the last stage. This result confirms that dissolutive wetting is dominated by dissolutive rate rather than by the total dissolutive quantity, and a high dissolution rate accelerates wetting.

      PubDate: 2017-09-14T07:35:59Z
  • Calculation of simultaneous chemical and phase equilibrium by the method
           of Lagrange multipliers
    • Abstract: Publication date: 31 December 2017
      Source:Chemical Engineering Science, Volume 174
      Author(s): Christos Tsanas, Erling H. Stenby, Wei Yan
      The purpose of this work is to develop a general, reliable and efficient algorithm, which is able to deal with multiple reactions in multiphase systems. We selected the method of Lagrange multipliers to minimize the Gibbs energy of the system, under material balance constraints. Lagrange multipliers and phase amounts are the independent variables, whose initialization is performed by solving a subset of the working equations. This initialization is the unconstrained minimization of a convex function and it is bound to converge. The whole solution procedure employs a nested loop with Newton iteration in the inner loop and non-ideality updated in the outer loop, thus giving an overall linear convergence rate. Stability analysis is used to introduce additional phases sequentially so as to obtain the final multiphase solution. The procedure was successfully tested on vapor-liquid equilibrium (VLE) and vapor-liquid-liquid equilibrium (VLLE) of reaction systems.

      PubDate: 2017-09-14T07:35:59Z
  • A weighted fuzzy Petri-net based approach for security risk assessment in
           the chemical industry
    • Abstract: Publication date: 31 December 2017
      Source:Chemical Engineering Science, Volume 174
      Author(s): Jianfeng Zhou, Genserik Reniers, Laobing Zhang
      As large amounts of hazardous chemicals are handled in the petrochemical industries, the plants in these industries are attractive for terrorists because they can cause great losses and have important social impact. Security risk assessment is important to determine the risk level of a plant in order to take targeted measures to reduce the security risk. Based on Security Risk Factor Table (SRFT) which covers the essential elements for the security risk assessment, a weighted fuzzy Petri-net (WFPN) based security risk assessment approach is proposed in this paper. This approach can easily model different relationships between the risk factors as well as their importance, and use the analysis method of Petri-nets to perform the risk assessment. Two WFPN models of security risk assessment are established according to different relationships between the factors, and a matrix operation based security risk inference method is developed. An illustrative example is used to demonstrate the approach. The results show that correctly determining and modeling the relationships among the risk factors is important to assess the security risk.

      PubDate: 2017-09-14T07:35:59Z
  • Liquid-liquid flow patterns and slug hydrodynamics in square microchannels
           of cross-shaped junctions
    • Abstract: Publication date: 31 December 2017
      Source:Chemical Engineering Science, Volume 174
      Author(s): Zan Wu, Zhen Cao, Bengt Sundén
      Flow patterns for water-butanol, water-toluene, water-hexane, water-oil and water/glycerol (weight ratio 60:40) mixture-oil two-phase flows were visualized in the cross-shaped junctions of three square glass microchannels with hydraulic diameters of 200µm, 400µm and 600µm. The aqueous phase is the continuous phase contacting the channel walls while the organic phase is the dispersed phase in the experiments. Three main flow pattern groups were observed, including the tubing/threading regime group, the dripping regime and the jetting regime. The flow regimes were mapped based on the Capillary number of the continuous phase and the Weber number of the dispersed phase. The flow rate ratio and the Capillary number of the dispersed phase were also employed to present flow patterns. The effects of hydraulic diameter of the square microchannels, flow rates, and physical properties, e.g., the interfacial tension and the viscosities of the aqueous and organic phases on flow pattern transitions were clarified. Besides, in the dripping regime, the dimensionless slug length can be scaled asa function of the Capillary number of the continuous phase for cross-shaped junctions. The slug velocity is linearly dependent on the average flow velocity in the dripping regime.

      PubDate: 2017-09-14T07:35:59Z
  • Combined iterative learning and delta-operator adaptive linear quadratic
           Gaussian control of a commercial rapid thermal processing system
    • Abstract: Publication date: 31 December 2017
      Source:Chemical Engineering Science, Volume 174
      Author(s): Wangyun Won, Kyungtae Park, Jiyong Kim
      Rapid thermal processing (RTP) units are used for various semiconductor fabrication steps mainly due to the short processing time, which results in a low thermal budget and improved product quality. In this study, we propose a comprehensive control system for the RTP unit by combining a linear quadratic Gaussian (LQG) controller, a constrained iterative learning controller (ILC), and a model parameter estimator. The control system is developed to resolve the issues caused by a short sampling time, which is required to meet the refractory control objectives of the modern RTP system (e.g., rapid ramping and a high degree of temperature uniformity). LQG control is selected because most required computations are conducted offline prior to each run and only minor computations are conducted in real time. The LQG control is constructed in a Smith predictor configuration so that a delayed model can be easily incorporated. The LQG control algorithm is modified from the standard formulation to include a quadratic penalty term for input deviation from the average value, to restrain the inputs from violating their constraints in real-time operation. The control algorithm and process model are developed in delta form so that the effect of the truncation error on the model accuracy can be alleviated at a high sampling rate. The constrained ILC updates the feedforward signal of the LQG controller in a batch-wise manner to further increase the temperature uniformity and to ensure that the inputs satisfy their constraints. To overcome model discrepancy from an actual system (patterned wafer), a small number of tunable parameters that can modify the major characteristics of the process model are incorporated into the identified state-space model (bare wafer) and are updated by a model parameter estimator. The performance of the proposed control system is validated in a numerical process, which is precisely constructed through identification experiments in a commercial 12-inch RTP unit.

      PubDate: 2017-09-14T07:35:59Z
  • Thermal conductivity and viscosity of nanofluids: A review of recent
           molecular dynamics studies
    • Abstract: Publication date: 31 December 2017
      Source:Chemical Engineering Science, Volume 174
      Author(s): Fatemeh Jabbari, Ali Rajabpour, Seifollah Saedodin
      The heat-transfer enhancement of nanofluids has made them attractive and the subject of many theoretical and experimental researches over the last decade. Of the theoretical approaches employed to investigate nanofluid properties, molecular dynamics (MD) simulation is a popular computational technique that is widely used to simulate and investigate thermophysical properties of nanofluids. In this paper, we review and discuss the MD studies conducted on the thermophysical properties of nanofluids, considering the thermal conductivity and shear viscosity as two important factors for the industrial application of nanofluids. In this study, after introducing different MD methods to calculate those parameters, we classify and review various influential effects including the volume fraction of nanoparticles, nanofluid temperature, Brownian motion of the nanoparticles, as well as the nanoparticle shape and size in terms of the thermal conductivity and viscosity of nanofluids. Viscosity has been studied to a lesser extent than the thermal conductivity of nanofluids. In our review, we note the similarities and differences between previous MD reports on nanofluids, and we highlight gaps and potential ideas that may be of interest for future studies.

      PubDate: 2017-09-14T07:35:59Z
  • Pressure drop, void fraction and wave behavior in two-phase non-Newtonian
           churn flow
    • Abstract: Publication date: 31 December 2017
      Source:Chemical Engineering Science, Volume 174
      Author(s): Ke Wang, Fan Jiang, Bofeng Bai, Teck Neng Wong, Fei Duan, Martin Skote
      Many commonly used industrial fluids display non-Newtonian effects. Their rheology exerts a strong influence on flow structure, interface fluctuation, pressure drop, heat transfer and many other flow characteristics. Owing to the complexity of churn flow, knowledge of the flow characteristics with non-Newtonian fluids is not well documented in existing literature. In the present study, we employ the power-law model to describe the non-Newtonian fluid behavior and establish an analytical model to predict pressure gradient, void fraction and wave behavior in churn flow. One churn flow unit is carefully divided into two parts (the falling film region and the wave region) and analyzed separately. The results indicate that liquid viscosity significantly affects the variations of pressure gradient, void fraction, velocity profiles, film thickness and wave behavior. These findings will provide insight into the effect of viscosity on flow structures and benefit a better understanding of the non-Newtonian churn flow.

      PubDate: 2017-09-14T07:35:59Z
  • Computationally based analysis of the energy efficiency of a CO2 capture
    • Abstract: Publication date: 31 December 2017
      Source:Chemical Engineering Science, Volume 174
      Author(s): Bojan Vujic, Alexander P. Lyubartsev
      We propose a model for thermodynamic evaluation of the energy efficiency of a CO2 capture in a temperature-pressure swing adsorption. Major parts of this model are computational prediction of the adsorbed gas loading as a function of temperature and partial CO2 pressure, evaluation of the energy expenses under specified conditions for the working capacity, regenerability of the sorbent and purity of the captured CO2, as well as determination of the most optimal desorption conditions in terms of desorption pressure and temperature. The proposed model can be applied for fast evaluation of the energy costs of the CO2 capture process with the use of both experimental or simulation adsorption data with respect to pressure and temperature. We tested this model analyzing data obtained from Grand Canonical Monte Carlo simulations for more than thousand different zeolite structures. Within our approach it is possible to evaluate a theoretical limit of the energy expenses for each specific material and to use the proposed method in screening different structures for the most efficient sorbent material from the energy efficiency point of view under specified requirements for the working capacity of the process, regenerability and purity of captured CO2. We show that setting realistic from the industrial point of view parameters of the CO2 capture cycle leads to substantial reduction of the number of suitable zeolite structures, and to increase of the energy penalty of the CO2 capture compared to evaluations based on minimization of the parasitic energy only.
      Graphical abstract image

      PubDate: 2017-09-14T07:35:59Z
  • Numerical studies of shear-thinning droplet formation in a microfluidic
           T-junction using two-phase level-SET method
    • Abstract: Publication date: 31 December 2017
      Source:Chemical Engineering Science, Volume 174
      Author(s): Voon-Loong Wong, Katerina Loizou, Phei-Li Lau, Richard S. Graham, Buddhika N. Hewakandamby
      A conservative level-set method (LSM) embedded in a computational fluid dynamics (CFD) simulation provides a useful approach for the studying the physics and underlying mechanism in two-phase flow. Detailed two-dimensional (2D) computational microfluidics flow simulations have been carried out to examine systematically the influence of different controlling parameters such as flow rates, viscosities, surface wettability, and interfacial tensions between two immiscible fluids on the non-Newtonian shear-thinning microdroplets generation process. For the two-phase flow system that neglects the Marangoni effect, the breakup process of shear-thinning microdroplets in cross-flowing immiscible liquids in a microfluidic device with aT-shaped geometry was predicted. Data for the rheological and physical properties of fluids obeying Carreau-Yasuda stress model were empirically obtained to support the computational work. The simulation results show that the relevant control parameters mentioned above have a strong impact on the size of shear-thinning droplets generated. Present computational studies on the role and relative importance of controlling parameters can be established asa conceptual framework of the non-Newtonian droplet generation process and relevant phenomena for future studies.

      PubDate: 2017-09-14T07:35:59Z
  • An analytical model for relative permeability in water-wet nanoporous
    • Abstract: Publication date: 31 December 2017
      Source:Chemical Engineering Science, Volume 174
      Author(s): Tao Zhang, Xiangfang Li, Zheng Sun, Dong Feng, Yanan Miao, Peihuan Li, Zenghua Zhang
      A relative permeability model for gas-water two phase flow in water-wet nanoporous media is proposed based on the continuity equation with modified non-slip boundary in a single nanotube and the pore size distribution (PSD) of the media. The present model takes into account the nanoscale effects including gas slippage in the entire Knudsen range, multilayer sticking (near-wall structural water film) and the quantified thickness of water film. The flow model in single nanotube and relative permeability model in nanoporous media have been validated by comparing with the various molecular simulations, experimental data, and analytical models. The results show the nanoscale effects play an extremely significant role in determining both the gas and water phase relative permeability in nanoporous media: the gas phase relative permeability increases dramatically due to the gas slippage effect, especially at low water saturation; the multilayer sticking of the water film will reduce the water phase relative permeability as well as slightly decrease gas phase relative permeability; the flow of water film has a negative impact on both the gas and water phase relative permeability. Additionally, logarithmic normal distribution function is adopted to characterize PSD, and the sensitivity analysis of PSD on the relative permeability are examined as well.

      PubDate: 2017-09-08T06:40:35Z
  • Co-Oriented Fluid Functional Equation for Electrostatic interactions
    • Abstract: Publication date: 31 December 2017
      Source:Chemical Engineering Science, Volume 174
      Author(s): Kai Langenbach
      In chemical engineering often functional groups like OH, CO, or NHx with an asymmetric charge distribution occur. Aside from polar interactions, such groups often show H-bonding interactions. The combination of both types is especially hard to describe with equations of state. This leads to the effect that including polar interactions for clearly polar pure compounds may lead to a worse description of mixtures containing this component. One possible reason for this behavior is that equations of state are usually based on perturbation theory that ignores the change in fluid structure due to interactions. This approximation is good for e.g. dispersive interactions, but is known to be bad for at least the gaseous phase of polar fluids up to moderate densities. The issue is addressed in this article by developing a perturbation theory around the target fluid rather than the reference fluid, as is usually the case. This makes it possible to include ordering effects into the equation of state and to calculate additional structural information in a fraction of the time used by typical methods like molecular simulation or integral equation theory. The perturbation theory is parameterized on the Stockmayer fluid’s structure and vapor-liquid equilibria, calculated from molecular simulation, and agrees quantitatively with them. It is verified on a second simple fluid, the shifted Stockmayer fluid, where the dipole is shifted along its axis away from the Lennard-Jones center. For this fluid also molecular simulations are performed for both structure and vapor-liquid equilibria. Both properties are predicted by the new equation of state and again agree quantitatively with simulation. The new theory is then applied to hydrogen chloride and shows improvements over models for existing theories. Namely, liquid density description is improved over a literature model for PCP-SAFT, where the dipolar nature of hydrogen chloride is considered, and vapor pressure description is improved over a literature model for PC-SAFT, where the weak H-bonding nature is considered. The number of parameters can be kept at three, as for the PCP-SAFT model, by using quantum mechanics results from literature for the dipole shift. The model shows improvements for the predicted vapor density compared to both models from literature. Aside from improving thermodynamic property description and prediction, the new theory allows the fast calculation of a fluid’s mutual orientation structure. This is useful e.g. for assessing availability of two reactant groups to each other, thereby allowing a better description of reaction kinetics. This has not been accomplished by any equation of state before.

      PubDate: 2017-09-08T06:40:35Z
  • Natural convection heat transfer utilizing ionic nanofluids with
           temperature-dependent thermophysical properties
    • Abstract: Publication date: 31 December 2017
      Source:Chemical Engineering Science, Volume 174
      Author(s): Alina-Adriana Minea, Wael M. El-Maghlany
      Ionic liquid based nanofluids are a very new and novel class of fluids used for heat transfer. The thermophysical properties of these new fluids are extremely encouraging in comparison to base ionic liquids and recommend these new fluids for solar applications. This paper deals with a numerical implementation of an ionic liquid nanofluid in a square enclosure considering two heating situations; bottom heating and lateral heating of the enclosure. Comparison with a regular alumina nanofluid in terms of Nusselt number is inserted. Thermophysical properties of these Ionic liquid based nanofluids were considered variable with temperature and the numerical results are correlated asa function of Ra and volume concentration (ϕ) for the two studied cases in the range of 104 ≤ Ra ≤106 and 0%≤ ϕ ≤2.5%. As an overall conclusion, this innovative class of heat transfer fluids reveals great potential in advanced heat transfer applications.
      Graphical abstract image

      PubDate: 2017-09-08T06:40:35Z
  • Simulation of bubbly flows with special numerical treatments of the
           semi-conservative and fully conservative two-fluid model
    • Abstract: Publication date: 31 December 2017
      Source:Chemical Engineering Science, Volume 174
      Author(s): Dongyue Li, Hasse Christian
      Bubbly flows are found in a large number of chemical engineering applications. For the computational fluid dynamics (CFD) simulations of such multi-phase flows, both physical models and numerical treatment are crucial to obtain robust and accurate results. In this numerical study, we investigate the two-fluid model (TFM) under challenging conditions such as phase segregation and inversion. For the phase segregation, a singular problem arises in the phase momentum and the two-phase k - ε equations when one phase fraction approaches zero. Another numerical issue is the accurate calculation of the drag coefficient, e.g., during the phase inversion. To address the singular problem, previous studies used a non-conservative formulation after dividing by the phase fraction; in our approach, we present a robust methodology for semi-conservative and fully conservative formulations. A special numerical treatment is introduced to the phase momentum equations and the turbulence equations, which avoids the singular problem in case of phase segregation. Concerning the drag force, two novel methods, the linear and the hyperbolic blending method, respectively, are presented to obtain accurate results. For testing the new numerical treatment, the analytical solution of a two-dimensional test case is first compared with the results predicted using a semi-conservative and a fully conservative formulation. The second test case investigated is a bubble column with different superficial velocities. The results from three-dimensional simulations using the novel formulations show good agreement with the literature data. Especially when phase segregation occurs, the semi-conservative and the fully conservative formulations using the two-phase k - ε model formulation converge.
      Graphical abstract image

      PubDate: 2017-09-08T06:40:35Z
  • Modelling cometabolic biotransformation of sulfamethoxazole by an enriched
           ammonia oxidizing bacteria culture
    • Abstract: Publication date: 14 December 2017
      Source:Chemical Engineering Science, Volume 173
      Author(s): Lai Peng, Elissavet Kassotaki, Yiwen Liu, Jing Sun, Xiaohu Dai, Maite Pijuan, Ignasi Rodriguez-Roda, Gianluigi Buttiglieri, Bing-Jie Ni
      Antibiotics such as sulfamethoxazole (SFX) are environmentally hazardous after being released into the aquatic environment and challenges remain in the development of engineered prevention strategies. In this work, a mathematical model was developed to describe and evaluate cometabolic biotransformation of SFX and its transformation products (TPs) in an enriched ammonia oxidizing bacteria (AOB) culture. The growth-linked cometabolic biodegradation by AOB, non-growth transformation by AOB and non-growth transformation by heterotrophs were considered in the model framework. The production of major TPs comprising 4-Nitro-SFX, Desamino-SFX and N4-Acetyl-SFX was also specifically modelled. The validity of the model was demonstrated through testing against literature reported data from extensive batch tests, as well as from long-term experiments in a partial nitritation sequencing batch reactor (SBR) and in a combined SBR+membrane aerated biofilm reactor performing nitrification/denitrification. Modelling results revealed that the removal efficiency of SFX increased with the increase of influent ammonium concentration, whereas the influent organic matter, hydraulic retention time and solid retention time exerted a limited effect on SFX biodegradation with the removal efficiencies varying in a narrow range. The variation of influent SFX concentration had no impact on SFX removal efficiency. The established model framework enables interpretation of a range of experimental observations on SFX biodegradation and helps to identify the optimal conditions for efficient removal.
      Graphical abstract image

      PubDate: 2017-09-02T00:37:21Z
  • Variable selection and training set design for particle classification
           using a linear and a non-linear classifier
    • Abstract: Publication date: 14 December 2017
      Source:Chemical Engineering Science, Volume 173
      Author(s): Stefan Heisel, Tijana Kovačević, Heiko Briesen, Gerhard Schembecker, Kerstin Wohlgemuth
      While particulate products are often characterized by their median diameter or the width of the particle size distribution, information is rarely given about the agglomeration degree of the product. To obtain this information, a tool combining image analysis and discriminant factorial analysis (DFA) was introduced in previous works. The accuracy of that method depended on the number of image descriptors selected, i.e. measurements describing each particle: few image descriptors resulted in rather poor classification while too many lead to an overfitting of the data. The aim of this study is twofold: First, we want to compare the classification accuracy of artificial neural networks (ANN) and DFA which, contrary to ANN, forms linear classifiers. Second, we want to provide an easy-to-implement procedure for generating particle classifiers. We used a qualitative measure called Proportional Similarity to test whether a subset selection of image descriptors was necessary to avoid an overfitting. The influence of the training set size was investigated as well as the transferability of the classifier on data obtained under different experimental conditions. The chemical systems used were l-alanine/water and adipic acid/water and the classes considered were single crystals, agglomerates, and gas bubbles. The results show that an ANN classifier provides higher accuracy and is more effective when only few image descriptors are available while DFA is simpler to create. Moreover, we show good transferability of classifiers trained on data of different experimental conditions. Based on our results, we provide guidelines for classification of particulate systems.

      PubDate: 2017-09-02T00:37:21Z
  • A mathematical investigation of the Turkevich organizer theory in the
           citrate method for the synthesis of gold nanoparticles
    • Abstract: Publication date: 14 December 2017
      Source:Chemical Engineering Science, Volume 173
      Author(s): Emmanuel Agunloye, Asterios Gavriilidis, Luca Mazzei
      Gold nanoparticles are commonly manufactured by the citrate reduction method, a synthesis method pioneered by Turkevich et al. (1951). Based on their experimental evidence, Turkevich et al. (1951) advanced the organizer theory, a nucleation-growth synthesis mechanism. Subsequently, Kumar et al. (2007) developed a mathematical model for the description of the synthesis, basing it on such a theory. However, this model has not been thoroughly tested. Recently, contrary to the evidence provided by Turkevich et al. (1951), other mechanistic descriptions of the synthesis, which emphasize the role of the pH of the solution, have been advanced in the literature. In this paper, we investigated the model of Kumar et al. (2007) for different conditions of pH, temperature and initial reactant concentrations. To solve the model, we used the numerical code Parsival, which is used for solving population balance equations. We tested the model for different synthesis conditions studied experimentally by various researchers, for which results are available in the literature. The model poorly predicted the experimental data because the Turkevich organizer theory does not account for the acid-base properties of chloroauric acid and sodium citrate. A new model, with a more accurate mechanistic description of the synthesis and of the chemistry involved, is therefore required.

      PubDate: 2017-09-02T00:37:21Z
  • Impact of granular segregation on the solid residence time and
           active-passive exchange in a rotating drum
    • Abstract: Publication date: 14 December 2017
      Source:Chemical Engineering Science, Volume 173
      Author(s): Shiliang Yang, Yuhao Sun, Liangqi Zhang, Jia Wei Chew
      Via the discrete element method, a three-dimensional partially filled rotating drum operating in the rolling regime is numerically simulated to investigate the solid residence and inter-region exchange behaviors in the active and passive regions, and their dependence on the operating parameters of rotating speed and particle diameter ratio of the binary-size mixture. The results demonstrate the effects of size-segregation of the binary-size mixture: (i) for both particle displacement and residence time, the magnitude of large particles are greater, and the magnitudes in the passive region are greater than that in the active region; (ii) the solid exchange rate between the two regions is greater for the small particles; (iii) although the solid exchange rate of each particle type evolves with time due to the evolving size segregation, the exchanging rate between the active and passive regions is proven to be global parameter, which is not influenced by size-segregation; (iv) changes in the rotating speed has a greater influence than that in particle diameter ratio in the ranges investigated. Collectively, these results shed more light on the impact of size segregation of a binary-size mixture on the characteristics of the rotating drum.

      PubDate: 2017-09-02T00:37:21Z
  • Electrostatics in gas-solid fluidized beds: A review
    • Abstract: Publication date: 14 December 2017
      Source:Chemical Engineering Science, Volume 173
      Author(s): Farzam Fotovat, Xiaotao T. Bi, John R. Grace
      Gas-solid fluidized beds, by their nature, are associated with intense and frequent collisions of solid particles with each other and with the vessel wall, causing tribo-electrification. Accumulation of electrostatic charges in fluidized bed reactors can result in severe problems such as agglomeration, wall fouling, nuisance and hazardous discharge, all reducing the process performance and raising significant safety concerns. Tribo-charging of particles in fluidized beds has also been exploited in a number of useful applications. In this review, the characterization methods of electrostatics and the mechanisms of charge generation and distribution in fluidized beds are presented, followed by an account of the interplay between the hydrodynamics and electrostatic phenomena. Furthermore, techniques of electrostatic charge control in fluidized beds are reviewed, and applications of tribo-electrostatic fluidization systems are summarized. Finally, computational fluid dynamics simulations of the electrostatic effects on the hydrodynamic characteristics of fluidized beds are outlined.

      PubDate: 2017-09-02T00:37:21Z
  • Effect of humidity on triboelectric charging in a vertically vibrated
           granular bed: Experiments and modeling
    • Abstract: Publication date: 14 December 2017
      Source:Chemical Engineering Science, Volume 173
      Author(s): Jari Kolehmainen, Petteri Sippola, Oskari Raitanen, Ali Ozel, Christopher M. Boyce, Pentti Saarenrinne, Sankaran Sundaresan
      Polyethylene particles were tribocharged in a glass container subjected to vertical vibration and the resulting charge per unit mass was measured. The experimental data in conjunction with discrete element method simulations coupled with a tribocharging model were used to deduce effective work function differences between the particles and the glass container at different humidity levels. In addition, we investigated the effect of different mass loadings on the particle charge, and found that the charge increased non-linearly when the mass loading was decreased. The proposed phenomenological model was found to capture this effect. Based on the estimated effective work function difference, it was predicted that a glass-walled fluidized bed of these particles would manifest vastly different hydrodynamics at 20 % and 60 % relative humidity levels. These predictions were confirmed experimentally.

      PubDate: 2017-09-02T00:37:21Z
  • Modelling the influence of mass transfer on fixed-bed photocatalytic
           membrane reactors
    • Abstract: Publication date: 14 December 2017
      Source:Chemical Engineering Science, Volume 173
      Author(s): Duy Dũng Phan, Frank Babick, Minh Tan Nguyen, Benno Wessely, Michael Stintz
      Photocatalytic membrane reactors have been recently considered as promising reactor types for photodegradation of organic compounds. In this work, a novel reactor concept named fixed-bed photocatalytic membrane reactor (FPMR), which relies on dead-end microfiltration of the catalyst particles, is introduced and studied. A quantitative model for evaluating the influence of mass transfer rate and intrinsic reaction rate on the overall photocatalytic degradation rate is developed and experimentally validated. The results show that the mass transfer rate contributes significantly to the overall reaction rate constant of the FPMR. They further reveal that the overall mass transfer coefficient and overall reaction rate constant of the reactor are greater than 4s−1. Those remarkably high rates are comparable to those of new photocatalytic microreactors which are two to three orders of magnitude higher than traditional photocatalytic reactors. Hence, the new reactor concept forms a powerful approach for designing photocatalytic microreactors.
      Graphical abstract image

      PubDate: 2017-09-02T00:37:21Z
  • Analysis of powder rheometry of FT4: Effect of particle shape
    • Abstract: Publication date: 14 December 2017
      Source:Chemical Engineering Science, Volume 173
      Author(s): Wenguang Nan, Mojtaba Ghadiri, Yueshe Wang
      Particle shape has a strong influence on bulk powder flow and its associated rheology. It promotes mechanical arching and adversely affects fast feeding and dosing. We use the FT4 powder rheometer of Freeman Technology to experimentally characterise the particle flow asa function of the shear strain rate, and to predict its dynamics for rod-shape particles using the discrete element method. The results show a strong realignment of the orientation of particles in the horizontal plane as the bed is sheared by the blade motion. The flow energy required for agitating a bed of rodlike particles is much larger than that of spheres and it increases with the aspect ratio, due to a combined effect of the coordination number and excluded volume. The flowability of rodlike particles can be improved by the addition of spheres, and can be well predicted by the mathematical model developed in this work. The bulk friction coefficient of the binary mixture is a linear function of the volume fraction of its components. The flow energy correlates well with the shear stress arising in front of the blade, considering the effect of the bulk friction coefficient.
      Graphical abstract image

      PubDate: 2017-09-02T00:37:21Z
  • Highly efficient and selective absorption of H2S in phenolic ionic
           liquids: A cooperative result of anionic strong basicity and cationic
           hydrogen-bond donation
    • Abstract: Publication date: 14 December 2017
      Source:Chemical Engineering Science, Volume 173
      Author(s): Kuan Huang, Xiao-Min Zhang, Lin-Sen Zhou, Duan-Jian Tao, Jie-Ping Fan
      A series of phenolic ILs containing different cations were synthesized and investigated for the absorption of H2S and CO2 in this work. It is interestingly found that the solubilities of H2S in these phenolic ILs are comparably high because of the strong interaction of basic phenolate anion with acidic H2S, while the solubilities of CO2 decrease significantly with the increase of cationic hydrogen-bond donation. Tetramethylguanidinium phenolate ([TMGH][PhO]), which is constructed with anion of strong basicity and cation of strong hydrogen-bond donating ability, is thus highlighted with both high solubilities of H2S (0.56mol/mol at 313.2K and 0.1bar, and 0.85mol/mol at 313.2K and 1bar) and high selectivities of H2S/CO2 (6.2 for the ratio of H2S solubility at 313.2K and 0.1bar vs. CO2 solubility at 313.2K and 1bar, and 9.4 for the ratio of H2S solubility at 313.2K and 1barvs. CO2 solubility at 313.2K and 1bar). Owing to the small molecular size of [TMGH][PhO], the absolute solubilities of H2S in it (2.68mol/kg at 313.2K and 0.1bar, and 4.08mol/kg at 313.2K and 1bar) are particularly fascinating, and much higher than other absorbents reported in the literature. Furthermore, [TMGH][PhO] is cost-effective in comparison with other functionalized ILs specifically designed for H2S capture, since it can be facilely synthesized from the one-step neutralization of readily available 1,1,3,3-tetramethylguanidine and phenol. The results obtained in this work indicate that [TMGH][PhO] is a promising candidate for the selective sweetening of natural gas.

      PubDate: 2017-09-02T00:37:21Z
  • Numerical simulation of compression breakage of spherical particle
    • Abstract: Publication date: 14 December 2017
      Source:Chemical Engineering Science, Volume 173
      Author(s): Tielin Chen, Qian Fang, Zejun Wang, Wenjun Zhu
      Understanding the breakage feature of granules has been an important study focus throughout the world for many years. The breakage mode depends on the extent of plastic flow, which cannot be explained by elastic solutions. In the paper, a numerical approach to particle breakage considering elastic-plastic behaviour is achieved using Finite Element Method (FEM). The numerical approach is validated by simulating the Brazilian test with a three-dimensional disk specimen. Then the breakage processes of spherical particle under compression are numerically modeled. The influence of different material mechanical properties is investigated and the consequences with respect to breakage processes are discussed. The predicted trends are in good agreement with experimental observations. The approach offers an effective way to investigate the breakage behaviour of granule, which would be helpful to make clear the whole process of the breakage mechanism.
      Graphical abstract image

      PubDate: 2017-09-02T00:37:21Z
  • Constants of explosive limits
    • Abstract: Publication date: 14 December 2017
      Source:Chemical Engineering Science, Volume 173
      Author(s): Ali M. Nassimi, Mohammad Jafari, Hossein Farrokhpour, Mohammad H. Keshavarz
      This work defines density factor as the ratio of before ignition density to after ignition density of the ignition mixture. This work provides an estimation method for explosive limits of various fuels under room temperature and pressure by showing that for a large universe of fuels, constant adiabatic flame temperature and density factor are appropriate approximations at the lower explosive limit while only a constant density factor might be an appropriate approximation at the upper explosive limit. Thus the assumption of a constant adiabatic flame temperature can be used in calculating lower explosive limit while the assumption of a constant density factor can be used in approximating upper explosive limit.

      PubDate: 2017-09-02T00:37:21Z
  • Characterization and secondary sludge dewatering performance of a novel
           combined aluminum-ferrous-starch flocculant (CAFS)
    • Abstract: Publication date: 14 December 2017
      Source:Chemical Engineering Science, Volume 173
      Author(s): Huanlong Peng, Songxiong Zhong, Jiangxin Xiang, Qintie Lin, Chuang Yao, Jiahua Dong, Guangcai Yin, Kun Yao, Siyuan Zeng, Jie Zhong
      The sludgedewateringperformance depends on the chemical and physical characteristics of sludge cakes. To investigate the relation between the sludge cake structural properties, the protein content in loosely bound extracellular polymeric substances (LB-EPS) and the dewatering performance of sludge, the sludge dewatering ability of a combined aluminum- ferrous- starch flocculant (CAFS) was evaluated for capillary suction time (CST), settling volume percentage (SV30), specific resistance to filtration (SRF), time to filter (TTF), dryness and the LB-EPS protein content. The dewatering mechanism was also probed by investigation of the compressibilities, SEM images andstructuralproperties of cakes. The results showed that CAFS could break sludge colloids easily and release more LB-EPS proteins. Cake microscopic structures and compressibility analyses indicated that the CAFS helped to form large incompressible dense cakes with discontinuous surfaces, containing a better adsorption capacity, which were closely related to the synergistic effect of cationic groups and starch mesh chains.
      Graphical abstract image

      PubDate: 2017-09-02T00:37:21Z
  • Sorption enhanced steam methane reforming on catalyst-sorbent bifunctional
           particles: A CFD fluidized bed reactor model
    • Abstract: Publication date: 14 December 2017
      Source:Chemical Engineering Science, Volume 173
      Author(s): Andrea Di Carlo, Ilaria Aloisi, Nader Jand, Stefano Stendardo, Pier Ugo Foscolo
      Sorption Enhanced Steam Methane Reforming (SE-SMR) has been proposed as an efficient novel technology to increase hydrogen yield and reduce the environmental footprint in comparison to state of art H2 production processes. Sorbent/catalyst materials characterized by stable behaviour over multiple reforming/calcination cycles may ensure to achieve almost stationary operating conditions utilizing a dual fluidized bed system (the reformer and the sorbent regenerator) with a solid circulation loop. Bifunctional, Combined Sorbent-Catalyst Materials (CSCM) are under development to integrate endothermic catalytic reforming and heterogeneous CO2 sorption in one particle, decrease mass and heat transfer resistances and reduce the solid hold-up in the reactors. This paper deals with the numerical simulation of a pilot scale bubbling fluidized bed SE-SMR reactor by means of a Two-Dimensional Computational Fluid-Dynamic (2D CFD) approach. The hydrodynamic picture is supplemented with a comprehensive Particle Grain Model (PGM) previously developed to describe the kinetics of catalytic and sorption functions, and successfully validated with micro-reactor reactivity tests and multi-cycle thermo-gravimetric sorption tests. The effect of repeated carbonation-calcination steps (the “history” of the granular material) is included in the computation of the reactor performance by utilizing the appropriate size of the sorbent grains in the carbonation rate expression. The numerical results show quantitatively the positive influence of carbon dioxide sorption on the reforming process, at different operating conditions, specifically the enhancement of hydrogen yield and reduction of methane residual concentration in the reactor outlet stream. A preliminary validation of CFD simulations is also carried out utilizing experimental data obtained from a pilot scale bubbling fluidized bed SE-SMR reactor (total bed mass≈14kg). An estimate is provided for the inward heat flow that would be required to operate the reactor in stationary temperature conditions: it is substantially reduced by the exothermic sorption process and could be satisfied by means of the solid circulation loop connecting the SE-SMR reactor to the high temperature calciner in the whole dual fluidized bed system.

      PubDate: 2017-09-02T00:37:21Z
  • A novel method for detecting and computing univolatility curves in ternary
    • Abstract: Publication date: 14 December 2017
      Source:Chemical Engineering Science, Volume 173
      Author(s): Nataliya Shcherbakova, Ivonne Rodriguez-Donis, Jens Abildskov, Vincent Gerbaud
      Residue curve maps (RCMs) and univolatility curves are crucial tools for analysis and design of distillation processes. Even in the case of ternary mixtures, the topology of these maps is highly non-trivial. We propose a novel method allowing detection and computation of univolatility curves in homogeneous ternary mixtures independently of the presence of azeotropes, which is particularly important in the case of zeotropic mixtures. The method is based on the analysis of the geometry of the boiling temperature surface constrained by the univolatility condition. The introduced concepts of the generalized univolatility and unidistribution curves in the three dimensional composition – temperature state space lead to a simple and efficient algorithm of computation of the univolatility curves. Two peculiar ternary systems, namely diethylamine – chloroform – methanol and hexane – benzene – hexafluorobenzene are used for illustration. When varying pressure, tangential azeotropy, bi-ternary azeotropy, saddle-node ternary azeotrope, and bi-binary azeotropy are identified. Moreover, rare univolatility curves starting and ending on the same binary side are found. In both examples, a distinctive crossing shape of the univolatility curve appears as a consequence of the existence of a common tangent point between the three dimensional univolatility hypersurface and the boiling temperature surface.

      PubDate: 2017-08-02T12:24:45Z
  • Influence of solids outlets and the gas inlet design on the generation of
           a gas-solids rotating fluidized bed in a vortex chamber for different
           types of particles
    • Abstract: Publication date: 14 December 2017
      Source:Chemical Engineering Science, Volume 173
      Author(s): Waldo Rosales Trujillo, Juray De Wilde
      Two design aspects of vortex chambers for the generation of gas-solids rotating fluidized beds are experimentally studied for different types of particles: the solids outlet(s) and the gas inlets. Efficient solids retention and minimal solids losses via the chimney are aimed at so that the gas and solids residence times can be controlled independently. The importance of a strong vortex in the central particle bed freeboard region is demonstrated. It is shown that separate, well-dimensioned and -positioned solids outlets prevent a significant presence of particles in the freeboard region, increasing the vortex strength in this region. This is found to be particularly important when fluidizing small/light particles. The ratio centrifugal force-to-radial gas-solid drag force that is generated by the gas injection is shown to also have an important impact. Theoretically it is shown that this ratio strongly depends on the particle characteristics and to what extent it can be increased by increasing the gas injection velocity, preferentially by reducing the gas inlet slot size and otherwise the number of gas inlet slots. Experiments with different vortex chambers and particles qualitatively confirm the theoretical expectations, but show that limitations are encountered. A very high gas injection velocity prevents efficient penetration of especially fine/light particles in the gas inlet jets which is detrimental for the transfer of tangential momentum between the gas and the particle bed. Slots smaller than the particle size are also shown to be inefficient, as they generate rotational motion of the particles around their own center of gravity.

      PubDate: 2017-08-02T12:24:45Z
  • Flow visualisation and modelling of solid soap extrusion
    • Abstract: Publication date: 14 December 2017
      Source:Chemical Engineering Science, Volume 173
      Author(s): M.P. Bryan, S.L. Rough, D.I. Wilson
      Ram extrusion of a solid granular soap was studied using three geometrically identical but differently-scaled extruders. The experimental design revealed deviation from the Benbow and Bridgwater (1993) extrusion model due to non-ideal, scale-dependent effects. Typically these effects, linked to the shear rate in the extruder, are absorbed into the model’s material pseudo-properties. The data were able to be represented using the Basterfield et al. (2005) model for extrusion flow which does include a shear rate as a variable. Flow visualisation in conjunction with fluid dynamics-based simulations showed, however, that the assumptions underlying the Basterfield et al. model are not appropriate for soap extrusion, despite the good agreement of the model with the experimental extrusion data. This highlights a need for care in interpretation of extrusion data, in that the limited information gathered about any given experiment, typically just the extrusion pressure, can lead to the generation of spurious parameters if the wrong model is applied.
      Graphical abstract image

      PubDate: 2017-08-02T12:24:45Z
  • Steering linear 1-alkene, propene or gasoline yields in ethene
           oligomerization via the interplay between nickel and acid sites
    • Abstract: Publication date: 14 December 2017
      Source:Chemical Engineering Science, Volume 173
      Author(s): K. Toch, J.W. Thybaut, M.A. Arribas, A. Martínez, G.B. Marin
      The ethene oligomerization performance of heterogeneous, Ni-based acid catalysts has been assessed by combining experimental measurements and Single-Event MicroKinetic (SEMK) modelling. In addition to the independently determined physisorption parameters, two catalyst descriptors, i.e., the ethene coordination enthalpy on the Ni-ion sites and the alkene protonation enthalpy on the acid sites, sufficed to adequately describe experimental data acquired on 1.8wt% Ni-SiO2-Al2O3 and 4.9wt% Ni-Beta zeolite. While Ni-sites ensure ethene dimerization, further alkylation, isomerization and cracking reactions occur on the acid sites. Unavoidably, alkylated species lead to product inhibition by hindering the accessibility of active Ni-ion sites for ethene. Very pronounced product physical adsorption was demonstrated to even result in reduced ethene conversion and, hence, catalyst activity. Through extensive reaction pathway analyses, guidelines for rational catalyst design for heterogeneous, Ni-based acid catalysts were proposed which are simulated to lead to selectivities of 60% towards 1-alkenes, 50% towards gasoline and 25% towards propene.
      Graphical abstract image

      PubDate: 2017-08-02T12:24:45Z
  • Modeling droplet dispersion in a vertical turbulent tubing flow
    • Abstract: Publication date: 14 December 2017
      Source:Chemical Engineering Science, Volume 173
      Author(s): Dmitry Eskin, Shawn Taylor, Shouxiang Mark Ma, Wael Abdallah
      Usually, during oil production, water and oil flow simultaneously in the wellbore. When water holdup in the borehole is small, water droplets may be dispersed into bulk oil making water breakthrough detection a challenging task. In this paper, a comprehensive engineering model of droplet dispersion is presented. Dispersion of droplets in a long vertical turbulent tubing flow is modeled by an Advection-Diffusion-Population Balance equation. The Prandtl Mixing-Length model of turbulence is used to describe the velocity profile across a tubing. The turbulence energy dissipation rate distribution across a pipe is calculated by an analytical equation. The fixed pivot method is employed for calculation of the population balance term of the governing equation. Droplet fragmentation is modeled using a recently developed droplet breakup model (Eskin et al., 2017). It is assumed that volume concentration of a dispersed phase does not exceed 10%. A computational code developed allows tracking evolution of droplet size distribution along a tubing. Model performance is illustrated by computations of the water in oil dispersion process. Effects of oil/water interfacial tension, well production rate and oil viscosity on dispersion are demonstrated.

      PubDate: 2017-08-02T12:24:45Z
  • Instability of uniform fluidization
    • Abstract: Publication date: 14 December 2017
      Source:Chemical Engineering Science, Volume 173
      Author(s): Chenxi Zhang, Weizhong Qian, Fei Wei
      Uniform gas solids distribution should be ensured to gain sufficient performance of fluidized beds. The highly chaotic entropy dissipation across solids bed will trigger non-uniform fluidization, although distributor plays an important role in obtaining homogenous gas stream. Hence, total solids pressure loading (Φ T ), the pressure drop ratio between solids bed and distributor, is introduced here to present their interaction. The boundary between uniform and non-uniform fluidization can be detected by stability analysis based on Prigogine’s minimum of entropy production principle, and this criterion for N parallel paths can be simplified into calculating the second derivative of pressure drop through one path with respect of Φ T . Furthermore, a phase diagram, illustrating the effects from operational parameter (Φ T ), geometrical characteristics of distributor (Cd ) and property of solids (Ga) on instability of uniformity, is attained to draw some useful conclusions of robust uniform fluidization.
      Graphical abstract image

      PubDate: 2017-08-02T12:24:45Z
  • Flow visualization and modelling of scrubbing liquid flow patterns inside
           a centrifugal wet scrubber for improved design
    • Abstract: Publication date: 14 December 2017
      Source:Chemical Engineering Science, Volume 173
      Author(s): Hassan Ali, Floren Plaza, Anthony Mann
      This paper presents an experimental and computational study of flow aspects in a commonly used centrifugal wet scrubber design. While manufacturers advertise up to 99.9% collection efficiency for dust particles >10µm in diameter, operators complain of compromised efficiency at low loads and droplet carryover at high loads. Similar problems are also faced by flue gas desulphurization towers. The industry requires satisfactory scrubber performance at varying factory conditions. Different scrubber flow parameters and dimensions were studied to discover the cause of the reported problems. Together with the CFD findings, the project delivered an improved understanding of the scrubbing liquid flow pattern which is crucial for high performance and was used as a basis to carry out design improvements.
      Graphical abstract image

      PubDate: 2017-08-02T12:24:45Z
  • A novel numerical approach for investigation of the gas bubble
           characteristics in stagnant liquid using Young-Laplace equation
    • Abstract: Publication date: 14 December 2017
      Source:Chemical Engineering Science, Volume 173
      Author(s): Hamed Gharedaghi, Ahmad Dousti, Javad Eshraghi, Pedram Hanafizadeh, Mehdi Ashjaee
      In the present study, the Young-Laplace equation was applied to simulate the adiabatic gas bubble growth from a submerged needle in stagnant liquid column. In order to solve the Young-Laplace equation the axisymmetric bubble height was used as input from experimental data. To increase the accuracy of Young-Laplace equations’ prediction during the bubble growth, the bubble was divided into four sections with the same height, and Young-Laplace equation was solved for each section individually. By dividing the bubble into four sections, the effects of viscosity and inertia forces within each section were reduced as compared to that of buoyancy and liquid-gas surface tension. Unlike the conventional Young-Laplace approach (one Young-Laplace equation for the entire bubble), the new approach was able to predict bubble characteristics reliably during the growth cycle. The bubble growth was investigated in a column of liquid with a triple contact line that fixed to the needle perimeter. To validate the numerical results, the bubble profiles that predicted by numerical simulation were compared with the experimental results. Experiments were performed by injection of air at constant gas flow rate of 600ml/h in the quiescent deionized water and SiO2 nanofluid. The nanoparticle concentrations were 0.05, 0.1 and 0.2wt%, and air flow injected from G14 and G17 standard needles. Eventually, evaluation of bubble characteristics, such as the bubble volume, the center of gravity, the instantaneous contact angle, and the bubble aspect ratio were investigated, and the effects of variation of liquid properties on the bubble characteristics were discussed. The results show that the present method can predict the bubble shape during 97.5% of growth time with mean absolute error of 6%. Furthermore, the results revealed that the bubble size decreased with increment of Bond number. Also, bubble instantaneous contact angle and bubble aspect ratio were almost irrelative to Bond number during the growth cycle.

      PubDate: 2017-08-02T12:24:45Z
  • Hydrogenated intramolecular cyclization of diphenylmethane derivatives for
           synthesizing high-density biofuel
    • Abstract: Publication date: 14 December 2017
      Source:Chemical Engineering Science, Volume 173
      Author(s): Genkuo Nie, Xiangwen Zhang, Lun Pan, Peijuan Han, Junjian Xie, Zheng Li, Jiawei Xie, Ji-Jun Zou
      Multi-cyclic hydrocarbons from biomass are sustainable alternative for jet fuel. Here we report an unexpected hydrogenated intramolecular cyclization of diphenylmethane derivatives synthesized by alkylation of bio-derived compounds. With the presence of commonly used zeolite-Pd/C dual catalyst, conventional hydrodeoxygenation (HDO) occurs to produce dicyclohexylmethane. However, when only hydrogenation catalysts like Pd/C or Ni is used, novel intramolecular cyclization takes place to produce perhydrofluorene with the selectivity as high as 96.0%. The two pathways were illustrated by step-by-step controlled reactions in detail and a mechanism was proposed to explain the reason for perhydrofluorene formation. Moreover, this intramolecular cyclization is versatile for diphenylmethane with OCH3 or OH group at any position. The synthesized perhydrofluorene shows density of 0.96g/mL, much higher than any biofuels reported and even higher than the widely used high-density fuel JP-10 derived from petroleum. It is believed that this biofuel can be excellent additive to improve the density of other jet fuels.
      Graphical abstract image

      PubDate: 2017-08-02T12:24:45Z
  • Electrokinetics desalination of water using fluorinated carbon nanotubes
    • Abstract: Publication date: 14 December 2017
      Source:Chemical Engineering Science, Volume 173
      Author(s): Abbas Panahi, Mohammad Hossein Sabour
      A molecular dynamics simulation was performed to investigate the transport properties of water, sodium and chlorine ions through double-end fluorinated carbon nanotubes (FCNT) under the horizontal electrical field. The present system consists of a carbon nanotube embedded in silicon membrane and two, water box placed at both sides of the membrane. The flow and structure analysis shows that FCNTs in a specific range of electrical field enhance the water flux. Furthermore, the flow significantly depends on carbon nanotubes radii. In FCNT (8,8) the water flux is increased to ∼215 H2O/ns which is 25% more than water flux in pristine carbon nanotubes. In FCNT (10,10) water flux increased to ∼600 H2O/ns which interestingly explain the improvement of water flux through fluorinated carbon nanotubes. The transport of water in FCNT and PCNT were scrutinized by other parameters such as hydrogen bonds, radial distribution function (RDF) and ionic current analysis. Results revealed the influence of fluorine functionalization on carbon nanotubes, headed for the increment of water transport through carbon nanotube based nanopore. Our results also put forward that fluorinated SWCNTs may be used as a design model in CNT-based water storage devices and water purification membranes.

      PubDate: 2017-08-02T12:24:45Z
  • Characterisation of reactive transport in pore-scale correlated porous
    • Abstract: Publication date: 14 December 2017
      Source:Chemical Engineering Science, Volume 173
      Author(s): Min Liu, Peyman Mostaghimi
      We apply a reactive transport model to study the effect of correlation length on dissolution and to characterise reactive transport in pore-scale correlated porous media. Porous media with different correlation lengths are derived from correlated fields. An efficient numerical model is employed to simulate dissolution on these geometries for a range of Péclet and Damköhler numbers. The solute concentration distribution is presented in porous media for both low and high correlation lengths. Four types of dissolution patterns are observed in various correlated porous media: face dissolution, uniform dissolution, wormholing and mixed dissolution. The permeability-porosity relationships are also studied in simulations of porous media with different correlation lengths. The permeability in larger correlation length media increases faster at the same Damköhler number. Dissolution patterns of all cases are plotted in a diagram and the effect of correlation length on reaction regimes are analysed. The findings show that larger correlation lengths can result in more uniform and wormholing types of dissolution but less face dissolution. Correlation length plays a critical role in characterising the reaction regimes during reactive transport.

      PubDate: 2017-08-02T12:24:45Z
  • Quantification of non-Newtonian fluid dynamics of a wormlike micelle
           solution in porous media with magnetic resonance
    • Abstract: Publication date: 14 December 2017
      Source:Chemical Engineering Science, Volume 173
      Author(s): Jennifer R. Brown, Jacob Trudnowski, Elmira Nybo, Katherine E. Kent, Thomas Lund, Amanda Parsons
      Nuclear magnetic resonance (NMR) pulsed gradient stimulated echo (PGStE) techniques were used to observe anomalous transport phenomena for flow of a non-Newtonian wormlike micelle solution through a model porous media. Understanding the flow behavior of wormlike micelle solutions in porous media is important due to the growing interest of these solutions in enhanced oil recovery. NMR velocity imaging was unable to discern differences in the flow field between shear-thickening wormlike micelle solution and water due to spatial resolution limitations. However, the probability of displacement, i.e. the propagator, was skewed towards slower velocities and long tails at high displacements for the micelle solution and incorporation of a fractional dynamics approach using the moments of the probability distribution showed a deviation from asymptotic Gaussian statistics.

      PubDate: 2017-08-02T12:24:45Z
  • Multi-scale modeling of diffusion and electrochemical reactions in porous
    • Abstract: Publication date: 14 December 2017
      Source:Chemical Engineering Science, Volume 173
      Author(s): T.D. Le, D. Lasseux, X.P. Nguyen, G. Vignoles, N. Mano, A. Kuhn
      A multi-scale model of diffusion/reaction at play in a porous electrode is developed and solutions to the physico-electro-chemical coupled problem are provided. This represents a key step to progress in the optimization of new efficient and innovative micro-electro-devices that needs to be addressed from a chemical engineering point of view. The pore-scale model based on Fickian diffusion in the porous medium and Nernstian layer and the electrochemical reaction governed by the Buttler-Volmer equation is upscaled using volume averaging to obtain a macroscopic model that describes the process on an effective equivalent medium. The validity and accuracy of the macroscopic model is successfully checked through the comparison with direct numerical simulations of the initial microscale model for amperometry tests. Predictions obtained from the upscaled model on the current intensity versus the scanning potential during voltammetry reveal to be in very good agreement with experimental results reported in the literature. These results show the capability of the macroscopic model to analyze the behavior of the porous electrode. In particular, it provides an efficient tool to study the dependence of the current intensity on the microstructure of the porous material and on the electrochemical parameters with the perspective of optimizing the electrode efficiency.

      PubDate: 2017-08-02T12:24:45Z
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